1) Does pulmonary capillary permeability to albumin change following hypovolemic or endotoxin shock? The permeability coefficient (P) is calculated from CL/Cp equals PA/(PA plus QL) where CL is the equilibrium lymph concentration for I125 RISA, Cp the simultaneous plasma concentration, A the pulmonary capillary area, and QL the pulmonary lymph flow rate. From right thoracic duct (RTD) lymph, following an intravascular I125 RISA injection, CL, and Cp will be determined simultaneously. "Perfused" pulmonary extravascular water (Voevw)is determined from simultaneous indicator dilution curves of I125 RISA and I131 iodoantipyrene. The pulmonary interstitial water vol. (Visw) will be measured with S35Na2SO4 in nephrectomized dogs. The total extravascular water (Vevw) will be determined gravimetrically and corrected for blood. The "perfused" pulmonary interstitial water vol. (Voisw) will be determined from: Voevw x Visw/Vevw. QL is calculated from Voisx/TRTD. 2) Is the 8-fold difference betwwen the RTD lymph rate (QRTD) and QL due to extrapulmonary reabsorption of water, or to an "excluded volume" of interstitial water, and is the equilibration curve in RTD lymph an accurate reflection of pulmonary interstitial fluid? The concentration-time curve for I125 RISA in VISW of small lung biopsies will be compared to the curve in RTD lymph. If the two curves are virtually identical, the "excluded volume" theory is the more probable; if the curve in Visw is lower than in lymph, reabsorption of water distal to the lung is more probable. 3) If there is a change in the amount of albumin and globulin carried by RTD lymph following hypovolemic or endotoxin shock, does it correlate with other indices of cardiovascular or respiratory function? Simultaneous RTD lymph and plasma concentrations of albumin and globulin, QRTD' and blood gases and pH will be measured in shock. Protein fluxes, pulmonary shunt fraction (QS/QT), and alveolar-arterial oxygen gradients will be calculated and correlated with each other and with cardiac output, and systemic pulmonary artery and wedge pressures. 4) Do corticosteroids influence the permeability of pulmonary capillaries to albumin or total flux of albumin or globulin the the RTD following hypovolemic or endotoxin shock? Dogs undergoi (Text Truncated - Exceeds Capacity)